The present invention relates to a novel and useful filtration system utilizing a heat exchanger.
Filtration systems such as those employing membranes have evolved into a preferred system of filtering solids from liquids. It has been found that membrane type filtration apparatuses may be scaled upwardly to fairly large capacities. Membrane filters also are capable of achieving a high degree of separation resulting in crystal-clear permeate. Particle size exclusion is also easily accomplished by selecting the requisite pore size of the membrane, generally from micron size to molecular dimensions. In addition, membranes may be obtained in various types of materials to match the characteristics of the products being separated.
A notable advance in the field of membrane separation may be found in U.S. Pat. Nos. 4,952,317 and 5,014,564 in which a membrane system using a vibratory motion to shear the face of the membrane is described, to successfully separate solids and liquids and prevent the membrane from being fouled. Although the vibratory shear system represents a notable advance in the field of membrane separation, limitations still exists due to the flow rate of the solids-liquid slurry being separated.
U.S. Pat. Nos. 4,834,874, 4,995,972, and 5,540,846 describe filtration processes in which heat is added directly to a filtration vessel, usually for the sake of vaporizing components therewithin.
U.S. Pat. No. 5,520,890 describes a solids-liquid slurry treatment apparatus which utilizes a multifaced catalytic reactor. The gaseous reactants are introduced into a slurry within the tubes of the reactor and a heat exchange medium is circulated around the outside of the tubes to effect a reaction within the reactor.
U.S. Pat. No. 5,556,539 describes an apparatus for separating a liquid by inducing shear in a membrane module. Heat is fed to a filtration device to boil the liquid mixture within the reactor to create a vapor drying apparatus.
A system for providing a heat exchange in a membrane filtration membrane for the purpose of regulating the viscosity on the liquid-solids mixture would be a notable advance in the field of separations.
In accordance with the present invention a novel and useful filtration system using a sub-system of heat exchange is herein provided.
The system of the present invention utilizes a membrane separator for accepting a solids-liquid inlet stream. The membrane filtration apparatus also includes a permeate and a concentrate outlet for permeate and concentrate streams. The source for the inlet solids-liquid inlet stream may be a holding tank, reservoir, or other similar component. Pump means delivers the solids-liquid inlet stream to the entry or inlet of the membrane filtration apparatus.
The inlet stream at the reservoir may lie at ambient temperature, but is heated by a heat exchanger which transfers heat from the permeate stream from the permeate outlet of the membrane filtration apparatus. In this regard, make-up heat may be selectively added to the solids-liquid inlet stream or to the exiting permeate stream from the membrane filtration apparatus. In any case, the heat exchanger reduces the viscosity of the solids-liquid stream entering the membrane filtration system. In many cases the heater used to elevate the permeate stream or the solids-liquid inlet stream may be a boiler of conventional configuration. In certain cases, a second heat exchanger may be employed to transfer heat between the solids-liquid inlet stream and the concentrate stream, also. In such an instance, the inlet stream would be split into first and second solids-liquid inlet streams, one passing through the first heat exchanger and the second passing through the second heat exchanger. Along these lines, a flow regulator may be also used to equalize the flow rates of the solids-liquid inlet stream and the exiting permeate stream from the membrane filtration apparatus. Likewise, another or second flow regulator may equalize the flow rates of the solids-liquid inlet stream to the flow rate of the concentrate stream. In any case, the membrane filtration system may comprise a vibration induced filtration system in which shear is applied across the membrane by an eccentric drive.
The concentrate stream exiting the concentrate outlet of the membrane filtration apparatus may be shunted to an evaporator. Thus, the concentrate stream may be further separated into solids and liquid which may be vaporized. The solids portion from the evaporator may be employed as a product or byproduct of the present process.
It may be apparent that a novel and useful filtration system has been described.
It is therefore an object of the present invention to provide a filtration system utilizing a membrane filtration apparatus which produces a decrease in viscosity of the inlet stream to the membrane filtration apparatus by the use of one or more heat exchangers.
A further object of the present invention is to provide a filtration system utilizing a membrane filtration apparatus in which the provision of heat to the inlet solids-liquid stream is able to decrease the size of a comparable non-heated membrane filtration apparatus by a large degree to produce an equal capacity.
Another object of the present invention is to provide a filtration system utilizing a membrane filtration apparatus which is far cheaper to manufacture and operate, due to a decrease in viscosity of the inlet solids-liquid stream.
A further object of the present invention is to provide a filtration system utilizing a membrane filtration apparatus in which the solids-liquid inlet stream may be optionally heated through the use of heat exchangers for use during all seasons, where the source of the inlet stream varies in temperature between winter and summer.
A further object of the present invention is to provide a filtration system utilizing a membrane filtration apparatus in which the use of heat exchangers to elevate the temperature of the solids-liquid inlet stream to decrease viscosity of the system prevents overdesigning of the system and result in the savings of capital.
A further object of the present invention is to provide a filtration system utilizing a membrane filtration apparatus in which the capacity of the system may be optionally boosted at certain times to coincide with peak and slack periods of demand, permitting shutting down of the system during slack times without substantial waste.
Another object of the present invention is to provide a filtration system utilizing a membrane filtration apparatus which obviates the need for an inventory of membranes since the life of the membranes may be extended by the use of heat exchangers to elevate the solids-liquid inlet stream to the membrane filtration apparatus.
Another object of the present invention is to provide a filtration system utilizing a membrane filtration apparatus which has wide application in water purification, waste treatment, separation of colloidal suspensions, and the like.
The invention possesses other objects and advantages especially as concerns particular characteristics and features thereof which will become apparent as the specification continues.